ANSWER:
It is prohibited to save from the monthly house expenses that your husband gives to you without his permission. If he gives this as a gift for you to utilize as you please as if it is pocket money, then you can save that and do with it what you like. But if he gives you this ONLY to use it for house expenses, you need his permission for that.
Fixed time deposits are usually riba based and this is one of the 7 major sins in Islam.